Artificial turf, also often referred to as synthetic grass, is a surface of synthetic fibers made to look like natural grass. It is most often used in sports applications. However, it is now being used on residential lawns and landscaping as well. Artificial turf stands up to heavy use and requires no irrigation or trimming. Domed, covered, and partially covered stadiums may require artificial turf because of the difficulty of getting grass enough sunlight to stay healthy. But, artificial turfs currently available still fail to provide the excellent shock absorbing properties of natural grass surfaces and also fall short in mimicking the volume effect of natural grass.
Today's generation artificial turfs are typically made from UV-enhanced polypropylene fiber or polyethylene fiber that is tufted into a woven synthetic primary backing that receives a secondary backing in form of a coating or laminate on the opposite side of the face fibers to give the turf dimensional stability and to aid fiber binding.
When installed, the turf's face (i.e., the grass “blades”) is generally given a layer of sand to augment water drainage and/or a layer of cryogenic rubber granules to help keeping the tufts more vertically oriented and to provide shock-absorbency.
The infill typically provides ballast and structure for the artificial turf, helping the fibers to stand and to provide a “cushion” effect when stepping over the turf. This protects the roots of the tuft fibers.
Currently, non-infill artificial turf refers to those artificial turf models with short pile height, narrow gauge (distance between rows), and high stitch rate. Artificial turfs that are used without such infill are typically made from shorter, denser polyethylene fibers that include even shorter crimped fibers to keep the tufts resembling grass blades upright. Some non-infill systems provide an underlay under the turf to provide cushioning.
Due to an ever increasing number of residential and commercial applications of artificial turf, artificial turf with improved properties that more and more resemble natural grass is sought after, as illustrated in the following examples.
GB 1,154,842 discloses raised tufted, bonded fibrous structures. A fibrous web of desired weight and structure was placed on top of another such web and the assembled fibrous structure then needle punched in a conventional single bed needle loom. On passage through the needle loom, fibres from one fibrous web are carried by the needles through the other fibrous web as the foundation layer and the needle penetration is controlled so as to ensure that the aligned fibres pass through the foundation layer and project beyond its surface as fibre tufts.
WO 2001/037657 A1 discloses a vertically draining, rubber filled synthetic turf. The vertically draining synthetic turf comprises a porous geotextile membrane positioned between an open graded aggregate layer and a sand layer. The synthetic turf also includes a pile fabric comprising a plurality of pile elements tufted to a woven or non-woven backing above the open graded aggregate layer. An infill layer consisting of resilient particles, preferably a mixture of high and low density rubber, is interspersed among the pile elements of the pile fabric. The backing layer may be solely a non-woven, in a single layer or in multiple layers. A suitable non-woven, dimensionally stable material is a polyester/nylon blend, spun-bound, non-woven material.
WO 2012/125513 A1 discloses a synthetic ground cover system for erosion control to be placed atop the ground, which includes a synthetic grass comprising a composite of one or more geo-textiles tufted with synthetic yarns. The synthetic ground cover also includes a sand/soil infill ballast applied to the synthetic grass and a binding agent applied to the sand/soil infill to stabilize the sand/soil infill against high velocity water shear forces. The system includes a synthetic turf which includes a backing and synthetic turf blades secured to the backing. The synthetic grass blades are tufted into the substrate or backing comprising a synthetic woven or non-woven fabric. The backing can be a single ply backing or can be a multi-ply backing, as desired. A filter can be secured to the substrate to reinforce the substrate and better secure the synthetic grass blades. Preferably, the at least one filter fabric may also comprise non-woven synthetic fabric.
As more artificial turf and less natural grass is used to cover the ground for an increasing number of applications, it is increasingly important to provide artificial turf that is eco-friendly.